The prior art has proposed probe-type electrical testers for determining presence of voltage in low powered circuits. An illustrative application in which such probe-type testers have long been commercially available is that of automotive electrical systems. These systems are of the direct current type and typically operate at a nominal voltage of twelve volts. Actual voltage, which may be provided for example by a vehicular AC generator or alternator, rarely exceed sixteen volts.
In trouble shooting vehicle electrical systems, a frequent step is that of determining if exposed metallic components and insulated conductors are energized. This is quickly and easily accomplished using a probe-type tester. The probe tester includes a first electrode which typically terminates in a sharp point which may either be rested on exposed metallic components, or forced to penetrate conductor insulation such that the probe, which is conductive, contacts the inner conductor being tested. The probe includes a lamp and a second electrode typically in the form of a flexible conductor terminating in a so-called “alligator clip”, which is a two-jawed clamp having a spring disposed to urge the jaws together. The probe-type tester is arranged such that the first electrode, the lamp, and the second electrode are disposed electrically in series. The alligator clip is typically fixed to a grounded portion of a vehicle. The sharp probe then is placed against an object being tested. Should the object being tested be energized, the lamp will illuminate, thus signaling the energized status thereof. The above apparatus and procedure are well known.
While existing probe testers work well, they suffer from certain practical deficiencies. For one, the probe point is usually exposed. As the probe point is typically sharp, an obvious hazard exists. Another deficiency is that testers of the prior art are fairly small and delicate, compared to other automotive tools such as wrenches and the like. In addition they are sufficiently long as to be slightly unwieldy. There is no convenient way of carrying a typical probe tester in ordinary use that is both safe and practical.
Some people carry probe testers in shirt pockets. The length of the typical tester is such that it is prone to falling from a shirt pocket. Because of its delicate nature, it can be damaged if stored with heavy steel tools or the like. And there remains the problem of protecting people and possessions from the sharp point of the probe.